*Long post ahead. Proceed at your own risk.*
This is a 2-parter theory by not me, but by @Samanalyse. I am only sharing it because I think it needs to be out there. The post is majorly about Kuhu, Varsha, MishKu and the doll story. The only thing I would like for you to keep in mind before any of you decide to skim through it is that Part-2 was written keeping the thought in mind that you have read and understand Part-1. So, read both warna your replies only won't make sense.
Part-1:
I fell in love with Kuhu and Varsha's relationship very early in the show and it prompted me to go back and watch as many bits and pieces of YRKKH as I could find with the two of them, as well as the early days of the show, to try and get an idea of Varsha's story. The more I watched, the more I loved sweet, sorted Varsha and all her relationships -- I think her abiding friendship with Akshara has to be my favourite though! I love that they always gave their friendship priority over the bhabhi-nanad relationship. 
I wrote this analysis in a PM to a friend around September, and that heartbreaking "mumma--ma" scene reminded me of it so I thought I'd share it here as well.
I really believe the key to Kuhu's character is Varsha. She loves and admires the heck out of her mom, and emulates her behaviour as much as she can. Varsha not only forgave her husband's infidelity with time, but even accepted Kuhu as her own child. That takes someone with a really big heart. On top of that she fought for Kuhu all her life. In my eyes, Varsha is the sole reason Kuhu is the confident, self-assured girl she is today, and for that reason Kuhu totally idolises her mother. So part of her resentment also comes from seeing how her mom, who is actually much more down to earch and sensible, is constantly treated as subordinate to her grandparents.
And this is where Mishti comes in, because of this really unusual situation, where the grandparents and parents have children of the same age. Mishti, in being the daughter of BM and BP automatically gets a higher position in the family hierarchy with less accountability -- as we see, she only has to answer to BM and BP. Kuhu, is answerable to her parents who are in turn answerable to theirs. I think most of Kuhu's resentment towards Mishti comes from these underlying inequalities -- their clashing personalities added fuel to the fire. Is it Mishti's fault directly? Not always. But does she rile up Kuhu's anger against this underlying inequality and bring out the worst in her with her patronising attitude? Definitely.
Now, if we observe the details closely, we can see that Varsha mostly raised Kuhu to tolerate the inequality in her family for as long as she had to and then get out of it as soon as possible (through marriage). Other than her occasional outbursts, Kuhu did just that in pretending to have this sisterly bond with Mishti. Varsha, for the most part, is extremely pragmatic. She sees that there isn't much scope to challenge BM and BP's authority or their hypocrisy without tearing the whole family apart, so she grits her teeth and pretends to be okay with it, all while equipping Kuhu to really shine once she is free of this household. This is why Varsha and Kuhu were so eager for her marriage right from the beginning of the show -- they lived their lives, trying not to raise their voices, not rebelling, pretending everything was great, with the single goal to get Kuhu out of this toxic environment as soon as possible (it's a totally different set of questions as to why marriage was the only way to do this, but I am thinking here within in the universe of the show, where that seems to be a given).
This is why Kuhu can't just walk out on this marriage so easily. She knows this wedding is the culmination of Varsha's lifetime of work, tolerating inequality and fighting for her, and this relationship with the RVs breaking would essentially render all of that work obsolete. That is also why both of them, in full acknowledgment that it was wrong to separate lovers, tried to keep Mishti and Abir apart -- that is just how important this marriage is to both of them: it's supposed to be Kuhu's escape and Varsha's peace of mind. And the thing is, Kuhu was ready for an arranged marriage, meaning she was ready to do the work of getting to know both her husband and his family over time -- so other than Kunal's antagonism (which is not even constant, with all the promising moments), what she is experiencing is exactly what she was prepared for, and so she is shining.
I think this is where the extreme reaction of the slap came from. The one thing Kuhu was most terrified about was hurting her mom or giving her any sense of failure -- she said so to Kunal multiple times. Kuhu would have done just about anything to protect Varsha and just when she thought she would succeed, she had to watch her mom's heart break for absolutely no reason. 
Every time Kuhu tries to sort things out slowly and carefully, Mishti comes tearing through with an impulsive move that ends up in the very destruction Kuhu was trying to avoid. It's not hard to see why she finally lost her patience, especially when that destruction involved the person she loves and admires most in the world this time around.😔
Part-2:
The events of the yesterday’s episode, and especially the way BM brought up an incident that happened when Mishti and Kuhu were children, make me believe that BM and BP never truly accepted Kuhu as their grand daughter and still hold the circumstances of her birth against her. It seems like Kuhu was expected to accept their decisions no matter how unfair they were (Mishti getting a dollhouse while she didn’t, Mishti getting two dolls while she got none), and simply be grateful that the family had taken her in and given her legitimacy at all. Mishti, on the other hand, came from Akshara’s sasural and adopting her was to ease the way for their jamaisa and his family so they automatically treated her “better.”
In fact, both the girls are victims of BM and BP’s terrible parenting and leadership. On the one hand, they favour Mishti to begin with and make Kuhu, Jasmeet, and Varsha feel small for raising their voices against that partiality, and then on the other blackmail Mishti into not expressing her emotions wrt Kuhu. BP gives Mishti the impression that she is jhelofying Kuhu while BM and Mishti give Kuhu more than ample reason to be angry in the first place. BP doesn’t see BM and Mishti’s instigation, because it is covert, and only sees Kuhu’s response because it is vocal so he assumes that Kuhu is the problem, which only further enrages Kuhu and makes Mishti feel put upon, when she actually has a significant hand in the root of the problem.
BM has some nerve to say that Varsha doesn’t see Kuhu’s mistakes when we have actually seen several occasions of Varsha either calling Kuhu out (Holi, numerous times when Kuhu has said something against Mishti) or letting her come to the understanding that she messed up on her own (rishta swap). It is BM who has never publicly accepted her daughter’s mistakes and has in fact enabled even her worst behaviour (Mishti faced no consequences for running away on her GD against BM’s wishes or for the way she handled the Nannu situation). Moreover, while BM was busy giving her gyan on how terribly Kuhu has treated Mishti, and how blind Varsha is to her own daughter's mistakes, Varsha was having a conversation with Kunal in which she not only avoided any mention/blame of Mishti and BM, she also stopped Jasmeet when she attempted to justify Kuhu's actions. I saw that as her saying, Kuhu has this blind spot and it's a major flaw but please don't let that overshadow all the love and respect in your relationship.
The worst part in all this is that BM has taught Mishti to be exactly like her — don’t confront people about their mistakes right away, pretend to be endlessly generous and magnanimous in public but then hold that mistake over their heads in private for the rest of their lives — and it is this very trait that has made Mishti utterly unable to form meaningful relationships with anyone who doesn’t constantly enable and praise her. Now BM is training Abir also so there remains very little hope for Mishti to introspect or grow. At least for Kuhu, Varsha and Jasmeet provide a balance with Varsha teaching her to prioritise keeping the peace and building relationships, and Jasmeet encouraging her to speak out when she feels belittled. As we saw when she first moved to RV house, she thrives in an environment where she is free to build relationships and where she is validated for her efforts and treated like an adult rather than dismissed as immature for being angry or upset. Mishti is definitely a huge trigger for her and she overreacts to situations that involve her, but from what I can see there is a long and troubling history to that behaviour that has very little to do with the maturity or lack thereof of either Kuhu or Mishti.
Shaming them for their issues and telling them to “figure it out” is going to accomplish absolutely nothing until the root cause of BM and BP’s faulty leadership is addressed, and for that to be addressed, their selfish motives in the parvarish of each of these girls has to be exposed.
P.S. Jo poora post quote karega, maata raani use paap chadhayengi
Kyunki Saas Bhi Kabhi Bahu Thi 2
